/Engine/Source/Runtime/SlateCore/Public/Application/SlateWindowHelper.h
The top-most (front-most) window is last in Z-order and therefore is added to the end of the list.
static void BringWindowToFront ( [TArray](API\Runtime\Core\Containers\TArray)< [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWindow](API\Runtime\SlateCore\Widgets\SWindow) >> & Windows, const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWindow](API\Runtime\SlateCore\Widgets\SWindow) > & BringMeToFront )